Phase diagram by changing (k_g, W) parameters. Three phases are indicated, disorder isotropic phase (I) (pink region), nematic I phase with highly aligned and very long microtubules (N_I) (blue region), and nematic II phase with relative short aligned microtubules (N_II) (yellow region). Solid dots are samples for which simulations are performed. The star symbols represent the typical cases used in the analysis in Fig. 3, for I phase (W = 28 nm, k_g = 45 nm/s) (see ESI-Movie1.mov), N_I phase (W = 10 nm, k_g = 65 nm/s) (see ESI-Movie2.mov), and N_II phase (W = 40 nm, k_g = 70 nm/s) (see ESI-Movie3.mov), respectively. Here the critical zippering angle α₀ = 0. The spontaneous catastrophe and collision induced catastrophe are not taken into account in this phase diagram. Other parameters are given in Table 1. For every data point we performed one single thread simulation with time 10⁵–5× 10⁵ s.